M27 bridge works

The News, Portsmouth

Behind the scenes of the works to repair the bridges at M27, the Hilsea interchange, Portsmouth

Transcript

00:00My name is Katia Linova, I'm the Head of Scheme Delivery for National Highways.

00:07So these bridges and this stretch of the M27 was built in 1975, so the bridges are now 50 years old.

00:14The bridges are built to last about 120 years before they nailed full replacement,

00:18but obviously some repairs need to take place just to make sure that it stays safe and lasts another 70 years.

00:25So what our inspections have shown that the concrete is delaminating, so falling away from the structure because of ingress of water.

00:32So what we're trying to do is waterproof the structure so the water ingress doesn't continue.

00:39Andy has described that we're doing some concrete repairs underneath and that what we're doing over the weekends

00:44is sealing the top of the structure with new waterproofing and repairing the drainage so that the structure stays safe.

00:52We could face a lane or even full closures of the M27 if we weren't to repair the structure

00:57because the defects could become such that we cannot run the motorway on top.

01:02So that's why we are preventatively trying to address these issues.

01:07And obviously it was initially marked for November to close, is that all still on schedule?

01:13Yes, it's still on plan. So the repairs underneath are mostly done and then we've got the four upcoming weekend closures

01:20with some contingencies in November. So at the moment, weather permitting, we're on track to finish the works in November.

01:26I think we do this kind of repairs across the country on all our structures.

01:30I think what we have found here is that the deterioration of the concrete is more because of the saline air and of the steel,

01:37but we do these sorts of repairs on our daily bread and butter.

01:42And just lastly, obviously, talking about kind of going in and getting the repairs and the things that are visible,

01:46obviously, once you're in there's obviously then you can kind of find more repairs.

01:49Is that going to happen along the way?

01:51Yes, we've had more to take out underneath. We don't yet know what we're going to find.

01:55Once we strip off the asphalt, then strip off the waterproofing and the top, we will do some concrete repairs.

01:59But we haven't been able to establish how much repairs we'll need to do at the top, so we will find that out at the weekend.

02:05But we've got enough contingency in the flooding for the weekend to make sure that we can open on Monday morning.

02:11This weekend coming up, we've got the West Bend garage road, which we call the South Bridge.

02:16We'll be planing out half the bridge, the north side, which is lane three, and part of lane two.

02:22Plan out that completely. We'll take out the curbs on both sides and replace those.

02:27Before we can place the curbs to go right down to the concrete deck and then we've got to re-waterproof that.

02:35Then we put the curbs back in, then the asphalt guys come along and relay the asphalt.

02:41And we'll let that in two days?

02:44We'll let that in two days.

02:46We'll start round about 11 o'clock on Friday night and the M27 will open at five o'clock number one.

02:56We've had these weekend closures a few times since the start of June, but so far you've always managed to get it done in time.

03:06Yes. Yes. 99.9% of the time, yes. That's real.

03:12It's been a challenge, but yeah, we've got one.

03:14Hopefully I haven't set you up for this weekend now.

03:16We've got the sun to be shining.

03:20Yeah, yeah.

03:21But speaking of it, I think we might have already covered it, but just in case you haven't, you know, kind of,

03:25one of the big challenges of this project so far has been kind of the weather and the mountain out there.

03:30Yes, everybody thinks that the sun's shining, it's great for concrete repair.

03:34It's not great for concrete repair.

03:36Everything dries out so quickly.

03:38You know, we have to wet the parent concrete down first, so when we put our material in,

03:44it doesn't absorb the water in our repair material, so then crack.

03:49The water content of our repair material is very low.

03:53Very low.

03:54Very low.

03:55So yes, it's been difficult, it's been a challenge.

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